The present invention relates to braiding methods and braided elements formed therefrom, and more particularly, to a method for braiding a striped braided element and the striped braided element formed therefrom.
The field of braiding, encompassing two-dimensional and three-dimensional braiding methods, devices, and systems, and braided elements formed by implementing thereof, is relatively well developed and documented about, including in the patent literature. Braiding is used in a wide variety of different fields, for example, textiles, electronics, aerospace, and medicine, for performing a variety of different applications, for example, harnessing, shielding, and/or reinforcing, materials and structures, requiring special or high performance properties, characteristics, and behavior.
In its most basic form, the process of braiding is based on converging a plurality of fibers, wires, threads, strings, yarn, or strands, herein, generally referred to as filaments, into a braiding zone which comprises a filament take-up device, as the filaments are supplied, tensioned, and unwound, by a plurality of filament carrier units. Each filament carrier unit comprises operative connections of a filament supply mechanism and a filament tensioning mechanism. The converging unwound filaments are taken up by the filament take-up device and form the two-dimensional or three-dimensional braided element. Each filament carrier unit may be made to supply multiple filaments that are grouped together and thus remain parallel and essentially contiguous throughout the braiding process and in the ultimate braided device. The braided device thus is composed of members, each member comprising either an individual filament or a contiguous group of filaments.
In two-dimensional braiding, the take-up device is ordinarily in the form of a rod, tube, or mandrel, herein, generally referred to as an axial braid configuring element, which is typically coaxial with a braiding axis extending through the braiding zone. The unwound members converging into the braiding zone and toward the braiding axis are braided and configured onto the outer surface of the axial braid configuring element, and form a two-dimensional braided element.
In three-dimensional braiding, the take-up device is ordinarily in the form of a multi-component mechanized device or mechanism, and directly takes up the unwound members as they converge into the braiding zone and form a three-dimensional braided element. In a three-dimensional braiding process, the braided members extend throughout the three-dimensional braided element in three dimensions, and are not limited to extending along the outer surface of an axial braid configuring element.
A commonly used implementation of conventional two-dimensional braiding method is the ‘maypole’ type machine, schematically illustrated in FIG. 1. Such a machine is commercially available from a number of manufacturers including Steeger USA, Inc., of Spartanburg, S.C., USA, or the Wardwell Braiding Machine Company of Central Falls, R.I., USA. In maypole type braiding machine 5, a plurality of members 14a, 14b are converged into a braiding zone BZ comprising a take-up device in the form of an axial braid configuring element 16 with a braiding axis BA, as the members 14a, 14b are supplied, tensioned, and unwound, by a plurality of synchronously configured and moving filament carrier units 10a, 10b and form a two-dimensional braided element 18 on the outer surface of the axial braid configuring element 16. The element 18 is characterized by at least two sets of helically wound members 14a, 14b having the braiding axis BA as their common axis. Each member in the set is characterized as having a common direction of winding, with the plurality of members of the set being axially displaced with respect to each other. The sets differ from each other in the direction of winding; with the first set 14a being wound in the opposite direction from the second set 14b. FIG. 1 is illustrated with 4 filament carrier units of each set, 10a and 10b respectively, however this is not meant to be limiting in any way.
Each filament carrier unit 10a, 10b is operatively connected to a gear or rotor type of driving mechanism (not shown), which in turn is operatively connected to a driving mechanism train or assembly (not shown) supported by a platform 17, according to a pre-determined configuration or design.
Braiding is ordinarily accomplished by synchronously rotating a first set of filament carrier units 10a (shown in black) in one direction, for example, clockwise, along a first circular serpentine track 20a (shown in grey), and a second set of filament carrier units 10b (shown in white) in the opposite direction, for example, counterclockwise, along a second circular serpentine track 20b (shown in white), periodically intersecting or crossing the first circular serpentine track 20a, in order to braid the unwound first set of members 14a and second set of members 14b as they converge into the braiding zone BZ toward the braiding axis BA and form a two-dimensional braided element 18 on the outer surface of the axial braid configuring element 16.
Two-dimensional braiding devices and machines are well described in patent literature, for example, U.S. Pat. Nos. 1,064,407 and 1,423,587, issued to Wardwell; U.S. Pat. No. 3,783,736, issued to Richardson; U.S. Pat. No. 4,616,553, issued to Nixon; U.S. Pat. No. 5,931,077, issued to DeYoung; and U.S. Pat. No. 5,974,938, issued to Lloyd. The teachings of such published literature and patents are fully incorporated herein by reference. Three-dimensional braiding methods, devices, and systems, are taught about in U.S. Pat. No. 6,439,096, issued to Mungalov et al.; U.S. Pat. No. 6,345,598, issued to Bogdanovich, et al.; U.S. Pat. No. 5,630,349, issued to Farley; and U.S. Pat. No. 4,615,256, issued to Fukata, et al.; the teachings of which are fully incorporated herein by reference.
There is a plethora of prior art teachings of different types of two-dimensional and three-dimensional braided elements, characterized by various types of two-dimensional and three-dimensional braid configurations or patterns of the members, respectively. Two well known prior art types of a two-dimensional braid configuration are: (a) a ‘one-over-two’ type of two-dimensional braid configuration or pattern, also known as a ‘regular’ or ‘herringbone’ pattern, and referred to herein as a 1×2 braid pattern, and (b) a ‘one-over-one’ two-dimensional braid configuration or pattern, also known as a ‘diamond’ pattern, and referred to herein as a 1×1 braid pattern.
A two or three dimensional braid pattern is ordinarily characterized by a uniform separation between the center axis of adjacent members in the set of members when measured along the circumference of the braid at any point along the longitudinal braid axis. This uniform separation is equal to the pitch of the braid divided by the number of members rotating in the same direction. It is to be understood by those skilled in the art, that there is no requirement that all filaments in a specific member be identical, nor is it required that all the members of a braid be identical. There is also no requirement that the separation be uniform over the longitudinal length of the braided element. There is therefore a uniform distance between the longitudinal center of each axially displaced member and the adjacent member being wound in the same direction at each circumferential section along the longitudinal braid axis of the braided element.
Exemplary embodiments of each of the above indicated two types, 1×2 and 1×1 braid patterns of a braided element, are illustrated in FIGS. 2A–2C, and are each briefly described immediately following in terms of using the previously described conventional braiding method using a maypole type machine 5 schematically illustrated in FIG. 1.
FIG. 2A is a schematic diagram illustrating an exemplary embodiment of a two-dimensional braided element characterized by a 1×2 braid pattern. In braided element 30 each member, for example, member 32, supplied, tensioned, and unwound, from filament carrier units 10a in a first set rotating in one direction, for example, clockwise, along a first circular serpentine track 20a, passes over and under two other members, for example members 34′ and 34″, supplied, tensioned, and unwound, from filament carrier units 10b in a second set rotating in the opposite direction, for example, counterclockwise, along a second circular serpentine track 20b. As shown in FIG. 2A, the braid pattern, and the distance between the center axis of adjacent members thereof, is uniform for any particular circumferential section along the longitudinal braid axis BA of the braided element 30.
FIG. 2B is a schematic diagram illustrating an exemplary embodiment of a two-dimensional braided element characterized by a 1×1 braid pattern. In braided element 36, each member, for example, member 38, supplied, tensioned, and unwound, from filament carrier units 10a in a first set rotating in one direction, for example, clockwise, along a first circular serpentine track 20a, passes over and under one other member, for example, member 40, supplied, tensioned, and unwound, from filament carrier units 10b in a second set rotating in the opposite direction, for example, counterclockwise, along a second circular serpentine track 20b. As shown in FIG. 2B, the braid pattern, and the distance between the center axis of adjacent members thereof, is uniform for any particular circumferential or radial section along the entire longitudinal braid axis BA of the braided element 36.
FIG. 2C is a schematic diagram illustrating an exemplary embodiment of a two-dimensional braided element characterized by a 1×1 bra uniformly comprising multiple adjacently parallel and essentially contiguous filaments. In braided element 42 each member comprising four adjacently parallel and essentially contiguous filaments, for example, member 44 comprising filaments 44a, 44b, 44c and 44d, supplied, tensioned, and unwound, from filament carrier units 10a in a first set rotating in one direction, for example, clockwise, along a first circular serpentine track 20a, passes over and under one other member comprising four adjacently parallel and essentially contiguous filaments, for example, member 46 comprising adjacently parallel and essentially contiguous filaments 46a, 46b, 46c and 46d, supplied, tensioned, and unwound, from filament carrier units 10b in a second set rotating in the opposite direction, for example, counterclockwise, along a second circular serpentine track 20b. 
As shown in FIG. 2C, for this 1×1 braid pattern in which each member comprises four adjacently parallel and essentially contiguous filaments, the distance between the center axis of all adjacent members of each set is uniform at each point along the longitudinal axis of the two-dimensional braided element 42, that is, for any circumferential section along the entire longitudinal braid axis BA.
In general, the use of fine wire as a filament in a uniform braid pattern is particularly advantageous in intraluminal medical devices. Unfortunately, such fine wire, in particular fine metallic wire having a cross-section or diameter smaller than approximately 100 μm, is relatively transparent to radiographic visualization. This lack of radio-opacity has led to various solutions and inventions, such as that described in U.S. Pat. No. 6,293,966 and U.S. Pat. No. 5,741,327 both to Frantzen and U.S. Pat. No. 6,503,271 to Duerig et al. Typically, these prior art solutions require the use of an additional material to be added to the intraluminal device, which may not be desirable.
Other proposed solutions include U.S. Pat. No. 6,527,802 to Mayer, which requires the use of a filament comprising a core and a clad, the core comprising a platinum-nickel alloy. Such a wire increases the cost and complexity of the medical device.
A further disadvantage to the prior art uniform braid pattern, particularly as applicable to a fine wire device, is the lack of structural rigidity supplied by the fine wire. One solution for this difficulty is shown in FIG. 2C, in which multiple filaments are combined into a single member. Unfortunately, utilizing multiple contiguous filaments increases the rigidity throughout the device, and does not allow for the possibility of having different combinations of rigidity at different points along the longitudinal axis.
There is thus a long felt need for, and it would be highly advantageous to have a braiding element having improved radio-opacity characteristics. Furthermore, it would be highly advantageous to have a braided element having different structural characteristics, which can be changed at different points along the longitudinal axis of the element.